Field of the Invention
The present invention relates to a printing apparatus, a method of controlling the same and a storage medium.
Description of the Related Art
In an image forming apparatus having a sheet feeding unit in which a plurality of differing sizes of sheets are stackable, setting of sizes of sheets stacked in the sheet feeding unit can be performed by various methods. For example, a method is known in which the image forming apparatus, in a case where it is provided, in the sheet feeding unit, with a sensor by which stacked sheet sizes are detectable, sets (stores) the sheet size detected using this kind of sensor as the sheet size corresponding to that sheet feeding unit.
On the other hand, there exist image forming apparatuses that are not provided with this kind of a sensor in order to reduce manufacturing costs. In these kinds of image forming apparatuses, for example, there is a method that is known in which a sensor, by which the size of sheets being conveyed is measurable, is provided and the size measured by this kind of sensor is set for the sheet feeding unit in accordance with the completion of conveyance of the sheets (printing completion) (Japanese Patent Laid-Open No. 11-301079). Also, in Japanese Patent Laid-Open No. 8-267851, a method is disclosed in which, upon power activation, or after opening and closing of the sheet feeding unit, because there is the possibility that the sheets stacked in the sheet feeding unit were replaced with the sheets of a differing size (the sheet size changed), size information that was set (stored) is updated.
In this kind of image forming apparatus, when print processing is performed based on a print instruction, in a case where the sheet size designated by the print instruction does not match a stored sheet size, a warning message is displayed which indicates that effect, and the user is prompted to replace the sheets with those of an appropriate size.
In image forming apparatuses (printing apparatuses), there are many cases where even if opening and closing of the sheet feeding unit is performed, sheets of the same size as before are supplied to the sheet feeding unit. For this reason, cases in which the sheet size information stored in the printing apparatus is updated only upon power activation without updating the sheet size information upon opening and closing of the sheet feeding unit are possible.
This kind of printing apparatus, when the sheets stacked in the sheet feeding unit are replaced by the user with sheets of a differing size in a state where sheet size information is stored, cannot change the sheet size information appropriately unless it enters an powered off state. As a consequence, when print processing is executed after replacement of the sheets, a print operation is suspended due to a mismatch between the stored sheet size and the sheet size designated by the print instruction, and a warning message prompting replacement of the sheets will be displayed. Because of this, convenience for the user is reduced.